public Node josephusKill(Node head,int m){
    if(head==null||head.next==head||m<1){
        return head;
    }

    Node last=head;
    while(last.next!=head){//not only left head one Node

         last=last.next;
    }//become a recicle node 

    int count=0;
    while(head!=last){
        if(++count==m){
            last.next=head.next;
            count=0;
        }
        else{
            last=last.next;
        }
        head=last.next;
    }
    return head;
}
